Effect of pre-strain during ageing on the maximum elongation of composite solid propellants and its modelling

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Nitrate ester plasticised polyether (NEPE) propellants, a kind of high‐energy solid propellant, were tested for their stabilizer content and Fourier transform infrared spectrum (FTIR) to study their ageing performance. On the one hand, a stabilizer consumption equation containing the ageing temperature, stabilizer content, and ageing time was established by analyzing the data of stabilizer content of NEPE aged at high temperatures (328, 333, 338, 343, 348, and 353 K). On the other hand, it was found that the second derivative spectral absorbance of 1598 cm−1 has a high linear correlation to the stabilizer content of NEPE propellant, and an equation, which can be used to calculate the stabilizer content of NEPE with FTIR data, was established. Thereafter, to prove the universality and accuracy of these two equations, FTIR testing of NEPE aged at room temperature (298 K) was carried out. Accordingly, the two other equations for stabilizer consumption at room temperature were derived by the FTIR data and the stabilizer consumption equation, respectively. They were consistent and the universality and accuracy of these equations were proven, and the feasibility of non‐destructive monitoring methods for NEPE propellants via FTIR was experimentally verified.

Section: Introductionmentioning

confidence: 99%

A Study on Consumption and Characterization of Stabilizer Content of NEPE Propellant via FTIR

Tao

Sui

et al. 2019

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Effect of Pre‐Strain Aging on the Microdamage Properties of Composite Solid Propellant

Zhou

Liu

et al. 2020

Accelerated aging tests under pre‐strain were conducted on HTPB‐based composite solid propellant with the goal of investigating the effect of pre‐strain aging on its microdamage properties. The tensile fracture morphologies, stress‐strain curve and dissipative energy density of propellant samples were analyzed. Results showed that there was no obvious dewetting macroscopically when the pre‐strain was less than 9 %, but the pre‐strain can still cause microdamage of propellant interface. The microdamage of propellant interface can be characterized by the critical dewetting strain, corresponded to pre‐strain by a linear law. The bonding performance between HTPB propellant matrix and solid filler was mainly affected by aging temperature. There was a critical temperature TC, For the HTPB propellant investigated in this study, the TC is between 65 °C and 70 °C. When aging temperature is below TC, there was no significant decrease in the overall levels of dissipated energy density, but decrease began significantly when the aging temperature is above TC.

A constitutive model of solid propellants considering aging and confinement pressure

Qin,

Zhang,

Zhang

et al. 2024

Aging during storage and confinement pressure during launch are the two major loading conditions that affect the integrity of solid rocket motors. In comparison to other component materials, solid propellants, as highly filled composites, have a low modulus and fracture toughness and are therefore common sources of failure. The key to improving the integrity of the solid rocket motor is in assessing the health of the solid propellants during storage or launch. To address this issue, we revised the previous model for the progressive damage viscoelasticity of solid propellants to include the effect of chemical aging during storage and the influence of confinement pressure during launch. Specifically, the increase in relaxation time due to aging and the nonequilibrium volume dilatation characteristics under triaxial tension and compression of solid propellants have been considered. To validate the developed model, standard relaxation tests and uniaxial tensile tests on solid propellants without aging were used to calibrate the model parameters. Furthermore, the model was validated by comparison with uniaxial tensile tests under confined pressure after aging and well predicts the aging temperature/time‐dependent mechanical responses of solid propellants. After validation, the developed model was used to study the influence of confinement pressure on microscopic damage evolution and macroscopic volume expansion. Overall, the developed model can be used for the analysis of the integrity of the solid rocket motor after the aging process.